In the following, a brief discussion of conventional components of current traffic control systems is provided.
Traffic signal controllers are used extensively through the United States and elsewhere around the globe. Most controllers are computer activated and use sophisticated software models to achieve optimization of traffic flow.
Years ago, digital computers began to be increasingly utilized in traffic control systems. Computers allowed creation of actuated controllers that have the ability to assist controlling traffic, in real-time, in response to actual traffic flow.
Generally, current controller operation can be divided into three primary categories: pre-timed, actuated (including both semi-actuated and fully actuated), and traffic response controller. Under the pre-timed operation, a master controller sets traffic signal phases and cycle lengths at predetermined rates based on historical data, whereas actuated controllers operate based on traffic demands as registered by the actuation of vehicle and/or pedestrian detectors.
Semi-actuated controllers maintain green lights (associated with traffic signals) on major streets, except when vehicles are detected on minor streets. If a vehicle is not detected, then the right of way associated with a major street is maintained. Fully-actuated controllers rely on detectors for measuring traffic flow on all approaches associated with an intersection and make assignments to the right of way in accordance with traffic demands.
The use of traffic response controllers has been gaining momentum in the recent years. Traffic response controllers are used, in conjunction with supplied traffic information, to control traffic flow. Therefore, it is important to ensure that information related to traffic can be collected in an efficient and cost-effective manner.
There are various methods in which traffic condition information may be collected in order to aid in optimizing traffic flow, through the use of traffic response controllers. For example, road sensor devices such as induction loops, traffic detectors and TV cameras mounted on poles may be used to monitor traffic conditions. Another way of supplying traffic condition information includes the use of mobile traffic units such as police, road service, helicopters and weather reports that may be provided by various information providing sectors. Finally, more recently, vehicle integrated mobile positioning and communication systems using GPS devices or similar vehicle-tracking/locating equipment are used to supply traffic related information to systems utilized to control and optimize traffic flow.
Although useful, the current traffic data collection methods and systems have various disadvantages. For example, there is a relatively high cost of capital investment needed to install fixed road devices, especially in existing road infrastructures, for monitoring traffic flow, and a potentially significant delay between when such infrastructure is planned for and when it is finally deployed, risking physically misplaced/misallocated infrastructure investment. In addition, there are a limited number of organizations, such as trucking, delivery and other service companies, utilizing GPS reporting systems. Moreover, there is a hurdle of establishing agreements to utilize information collected by such organizations. Finally, there are very few GPS or similar equipped vehicle-tracking/locating entities in service today. Therefore, the information provided by these few individual vehicles that include equipment for procuring and disseminating position information is insufficiently widespread and dense to allow conventional vehicular traffic control systems to make intelligent decisions related to traffic flow.